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Lee, Light-Horse Harry

(Encyclopedia)Lee, Light-Horse Harry: see Lee, Henry. ...

speed

(Encyclopedia)speed, change in distance with respect to time. Speed is a scalar rather than a vector quantity; i.e., the speed of a body tells one how fast the body is moving but not the direction of the motion. If...

tachyon

(Encyclopedia)tachyon tăkˈēŏnˌ [key], hypothetical elementary particle that travels only at speeds exceeding that of light. According to the theory of relativity, the speed of light is the limiting velocity fo...

refraction

(Encyclopedia)refraction, in physics, deflection of a wave on passing obliquely from one transparent medium into a second medium in which its speed is different, as the passage of a light ray from air into glass. O...

Cherenkov radiation

(Encyclopedia)Cherenkov radiation or Cerenkov radiation [for P. A. Cherenkov], light emitted by a transparent medium when charged particles pass through it at a speed greater than the speed of light in the medium. ...

hypersonic speed

(Encyclopedia)hypersonic speed: see aerodynamics. ...

supersonic speed

(Encyclopedia)supersonic speed: see aerodynamics. ...

Speed, John

(Encyclopedia)Speed, John, 1552?–1629, English historian and cartographer. He abandoned his trade as a tailor to engage in mapmaking. Many of his maps of parts of England and Wales were published in The Theatre o...

Michelson, Albert Abraham

(Encyclopedia)Michelson, Albert Abraham mīˈkəlsən [key], 1852–1931, American physicist, b. Strelno, Prussia, grad. Annapolis, 1873, and studied at Berlin, Heidelberg, and Paris. He was professor of physics at...

aberration of starlight

(Encyclopedia)aberration of starlight, displacement of the apparent path of light from a star, resulting in a displacement of the apparent position of the star from its true position; discovered by the English astr...